Upon performing a diagnostic on a blood vessel, it is necessary to observe not only whether or not there exists any change in a vascular diameter and a degree thereof due to plaque and the like, and a difference how the vascular diameter changes, concentrically or eccentrically, but also whether or not any abnormality exists, and positional information and composition information thereof, including information such as compensatory enlargement without changing the vascular diameter, a property of the plaque (a ratio of lipid), and a place where such abnormality exists. In recent years, by the improvement of spatial resolution and temporal resolution of the medial image diagnostic device, it is becoming possible to acquire information, such as whether or not any abnormality exists, the positional information and the composition information thereof, from a medical image.
In general, it is difficult to simultaneously provide information such as whether or not an abnormality exists, the positional information, and the composition information, using only one image. Conventionally, observations are performed by combining more than one image, such as a tomographic image orthogonal to a blood vessel and an image cut by a curved surface along a traveling direction of the blood vessel as described in the patent document 1, for instance. Furthermore, the patent document 2 describes that a display is created by superimposing information relating to depth, on an X-ray perspective projection image that is displayed as a guide image when PCI (Percutaneous Coronary Intervention) treatment is applied.